The present invention relates to a turbocharging device of an engine for a vehicle.
Conventionally, turbochargers have been provided to vehicles so as to supply a larger amount of intake air to engines. Moreover, devices are known that are each provided with a bypass passage bypassing a compressor of the turbocharger and a bypass valve for opening and closing the bypass passage, and switches, according to an operating condition of the engine, between a mode for forcibly inducting intake air by the turbocharger and a mode for leading the intake air to the bypass passage and not performing the turbocharging.
For example, JP2012-012990A discloses a device including two turbochargers, a bypass passage for bypassing compressors of the turbochargers, and a bypass valve for opening and closing the bypass passage. The device switches the turbocharger to operate according to the operating condition of the engine.
As described above, with such a device including two turbochargers, the bypass passage bypassing compressors of the turbochargers, and the bypass valve for opening and closing the bypass passage, oil contained in the intake air passing through the bypass passage adheres on the bypass valve, particularly a seating face of the bypass valve, becomes sticky, and stops the movement of the bypass valve or slows down the movement of the bypass valve. Thus, there is a case where a suitable intake control cannot be achieved.